This application claims the benefit of Japanese Patent application No. 2001-225411 which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to eyeglasses, and more particularly, to an end piece for a temple, a temple with an end piece, and a unit for an eyeglass frame.
2. Related Background Art
An eyeglass frame has a front part for supporting lenses or being supported by lenses (i.e., the front part is supported by lenses in rimless eyeglasses), a pair of temples, and a pair of hinges for connecting the front part with a pair of temples.
An eyeglass frame also has a pair of nose pads located between left and right lenses, and a pair of end pieces to be mounted to a pair of temples. The nose pads contact a user""s nose, and a pair of end pieces contact user""s ears, thereby the eyeglasses being supported on user""s head.
If an eyeglass temple is entirely made of metal, use of such eyeglasses makes a user feel cool and hard around his ears, giving him an unpleasant feeling. To avoid this unpleasant feeling, the temple""s end (drop end) that engages with user""s ear is covered with a plastic member, i.e., an end piece. The end piece was made of celluloid at first. There is a long hole in the end piece into which an end part of a metal temple is inserted. This end part of the metal temple is, hereafter, called a metal core of a temple. A diameter or size in cross section of the long hole is made a little smaller than a diameter or size in cross section of the metal core, so that the metal core is forcedly inserted into the long hall by applying force to the temple or the end piece is heated to be soften and then the metal core is inserted into the long hole.
The metal core runs through the long hole to its bottom. When the end piece is bent manually, the metal core is deformed plastically. Once the metal core has been deformed, the metal core keeps the end piece in a deformed shape, thereby the end piece being fit to a user""s ear and head. This deformation is called fitting.
However, the deformation is limited to a certain amount, and the celluloid end piece gives a user a hard feeling around his or her ear. Further, when a user wears eyeglasses with the celluloid end pieces for long hours, the portion of user""s skin that contacts the celluloid end piece is hurt, giving a user an unpleasant feeling and leaving a red mark on user""s skin. Though, at present, celluloid is replaced with cellulose propionate plastic or cellulose acetate plastic, the above problem has been existing. Then an end piece made of shape-memory plastic has been disclosed in Japanese Patent Application Laid-Open No. 8-15654 (lines 6-7 of paragraph 0020). This Japanese Patent Application is, hereafter, called prior art.
According to this prior art, the second embodiment of the prior art discloses, in the nineteenth paragraph on page 3, that shape-memory plastic of which glass-transition temperature (Tg) is set a little lower than the body temperature is used for an end piece. Once shape-memory plastic is warmed with user""s body, the end piece is softened and deformed so as to fit user""s head, contacting user""s head softly.
Meanwhile, nose pads also contact user""s skin directly. When a user wears eyeglasses with celluloid pads for long hours, the portion of user""s skin that contacts the celluloid nose pads is hurt, giving a user an unpleasant feeling and leaving a red mark on his or her skin as well as the celluloid end pieces. The prior art discloses that shape-memory plastic is used for nose pads to solve the problem.
However, such use of shape-memory plastic for end pieces and nose pads causes another problems. The first problem is that while a user is using eyeglasses with the end pieces of shape-memory plastic for a long time, a tip of the metal core breaks the bottom of the end-piece""s hole and protrudes from the end piece. The second problem is caused as follows. When high heat is added to any part of a temple other than the metal core, the heat is transmitted to the metal core because the metal temple has a high heat conductivity, and then the heat softens the end piece more than necessary, so that the end piece is prone to be removed from the metal core.
Meanwhile, a nose pad is mounted to a metal frame of eyeglasses by using a nose-pad metal core that is almost covered with material of a nose pad. Using shape-memory plastic as a material for a nose pad, the same problems as those in the end piece arise. That is, (1) the first problem is that a metal core protrudes from the nose pad of shape-memory plastic. (2) The second problem is that the metal core is prone to be removed from the nose pad when high heat is conducted to the metal core.
It is an object of the present invention to provide a unit for an eyeglass frame in which a metal member covered with shape-memory plastic does not protrude from the shape-memory plastic even if eyeglasses are used for a long time.
It is further object of the present invention to provide a unit or a part for an eyeglass frame in which a metal member covered with shape-memory plastic is not removed from the shape-memory plastic even if high heat is conducted to the metal member.
The present invention can be applied to units or parts for an eyeglass frame, such as an end piece and a nose pad, which contact a user""s body.
In order to achieve the above objects, according to one aspect of the present invention, there is provided a unit for an eyeglass frame comprises a metal core, an end piece substrate made of hard plastic of which heat deformation temperature is higher than 50 degrees centigrade, and an end piece cover made of shape-memory plastic of which glass transition temperature of between 20 degrees centigrade and 40 degrees centigrade, wherein, the metal core is embedded in the end piece substrate, and the end piece cover locates outside the hard plastic substrate, so that the end piece cover contacts a human body.
By using shape-memory plastic in a limited range of glass-transition temperature, i.e., between 20 degrees centigrade and 40 degrees centigrade (preferably, between 30 degrees centigrade and 35 degrees centigrade), the present invention can properly utilize a nature of shape-memory plastic. Further, by covering the metal core with the hard plastic of which heat deformation temperature is higher than 50 degrees centigrade (preferably, higher than 70 degrees centigrade), the present invention can avoid the first problem that the metal core protrudes from the end piece and the second problem that the metal core is prone to be removed from the end piece.
Furthermore, in accordance with the present invention, eyeglasses comprise a pair of eyeglass lenses, a bridge that connects the eyeglass lenses, and a pair of metal temples, wherein an end part of each of the metal temples is embedded in a substrate made of hard plastic of which heat deformation temperature is higher than 50 degrees centigrade, and shape-memory plastic of which glass-transition temperature is between 20 degrees centigrade and 40 degrees centigrade is disposed outside the substrate, the shape-memory plastic being disposed where a human body contacts.
Furthermore, in accordance with the present invention, eyeglasses comprise a pair of eyeglass lenses, a bridge that connects the eyeglass lenses, a pair of temples, a pair of nose pads, wherein each of the nose pads includes a metal core, a substrate in which the metal core is embedded and which is made of hard plastic of which heat deformation temperature is higher than 50 degrees centigrade, and shape-memory plastic of which glass-transition temperature is between 20 degrees centigrade-40 degrees centigrade is disposed outside the substrate, the shape-memory plastic being disposed where a human body contacts.
Furthermore, in accordance with the present invention, a metal temple having an end piece made of shape-memory plastic of which glass-transition temperature is between 20 degrees centigrade and 40 degrees centigrade, a part of the metal temple being used as a metal core which is inserted into the end piece, wherein the metal core is embedded in a substrate made of hard plastic of which heat deformation temperature is higher than 50 degrees centigrade, the shape-memory plastic being disposed outside the substrate.
Furthermore, in accordance with the present invention, an end piece including a substrate that is made of hard plastic of which heat deformation temperature is higher than 50 degrees centigrade and has a long hall into which a metal core of a metal temple is inserted, and shape-memory plastic that has a glass-transition temperature of between 20 degrees centigrade and 40 degrees centigrade and is disposed outside the substrate.
Furthermore, in accordance with the present invention, the hard plastic may be thermoplastic cellulose plastic.